from the GNU version of the Collaborative International Dictionary of English

adj. Not to be coerced; incapable of being compelled or forced.

adj. Not capable of being reduced to the form of a liquid by pressure; -- said of any gas above its critical temperature.

adj. That can note be confined in, or excluded from, vessels, like ordinary fluids, gases, etc.; -- said of the imponderable fluids, heat, light, electricity, etc.

from The Century Dictionary and Cyclopedia

Not to be coerced or compelled; incapable of being constrained or forced.

In physics, incapable of being reduced to a liquid form by any amount of pressure. Certain gases were formerly supposed to have this property. See gas.

In physical:

Incapable of reduction to tangible condition by pressure: applied to forms of energy, such as heat and electricity, when they were thought of as extremely subtile fluids.

Etymologies

in- +‎ coercible (Wiktionary)

Examples

Pacific Ocean shall pour into the Atlantic; when man will become more precious than fine gold, and when his ambition will be to subdue the elements, not to subjugate his fellow-creatures, to make fire, water, earth and air obey his bidding, but to leave the poor ethereal mind as the sole thing in Nature free and incoercible.

Liberty of thought and action, and incoercible desire to be free from governmental, traditional, ultra-ecclesiastical, or Shint [= o] influence -- in a word, protestantism in its pure sense, is characteristic of the great sect founded by

We are that incoercible force that wants to do what I have repeated so many times and I say it you again today, to do what Cervantes express in his Don Quixote: change the giants into windmills, and not the windmills into giants.